A foldable chair may be configured as a walking stick chair for use of people having inferior physical condition. Taiwanese Patent Application No. 102112330 discloses a conventional walking stick chair including a stick and a sleeve that is slidable along the stick. The conventional walking stick chair is convertible between a folded state and an unfolded state by moving the sleeve along the stick. The sleeve can be positioned relative to the stick for retaining the conventional walking stick chair in the folded or unfolded state. However, positioning of the sleeve relative to the stick can only indirectly keep a support leg of the conventional walking stick chair in folded or unfolded state. That is, the support leg may not be retained steadily at a predetermined position relative to the stick when the sleeve is positioned.